Developmental mode and adult morphology in bufonid frogs: A comparative analysis of correlated traits

The influence of life history evolution on morphology in frogs of the family Bufonidae was explored using the comparative method. Heterochronic and heterotopic phenomena associated with the evolution of endotrophy have predictable consequences on subsequent morphogenesis. Loss of a free living, feeding larval stage (evolution of endotrophy) is proposed to be an important catalyst of morphological changes including reduction, fusion, loss of bones, and novel arrangements of elements. Because information on the embryological development of most taxa included in this study is not available, selection of traits and interpretation of patterns were based on theoretical models and empirical data from other groups.;A phylogenetic hypothesis of relationships among bufonid frogs was constructed based on 12S and 16S ribosomal DNA. This hypothesis was compared to previous hypotheses and was used in a comparative analysis exploring how changes in developmental mode have influenced morphological evolution in the family.;A review of the Andean genus Osornophryne is presented and aspects of the morphology, natural history, and distribution of its member species are discussed. This taxon is representative of a highly derived clade of toads and aspects of its biology may be representative of other poorly---known taxa. Two new species of Osornophryne from the Andes of Ecuador are described, further illustrating the existence of high levels of species diversity and morphological variation among endotrophic toads.